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排序方式: 共有1297条查询结果,搜索用时 15 毫秒
101.
Binh Thi Thanh Nguyen Jin Qiang Ang Chee-Seng Toh 《Electrochemistry communications》2009,11(10):1861-1864
A model K+ sensor using Prussian blue nanotubes is fabricated by electrochemical deposition of Prussian blue (PB) within the nanochannels of a porous metal-coated membrane with partially covered pore openings. The PB nanotube sensor exhibits excellent stability giving reproducible peak potentials up to 500 measurement cycles, a very low detection limit of 2.0 × 10−8 M and extremely wide logarithmic linear ranges between 5.0 × 10−8–7.0 × 10−4 M and 7.0 × 10−4–1.0 M. Negligible interferences by Na+, Mg2+ and Ca2+ are observed and a rapid analysis time of 30 s is readily achieved. The ease of electrodeposition, high stability of PB nanotubes and outstanding analytical performance which surpasses conventional PB voltammetric and potentiometric sensors demonstrates potential sensing applications including ion sensors and biosensors using PB and other metal hexacyanoferrate nanotubes. 相似文献
102.
Jürgen Caro 《中国化学快报》2009,20(2):250-252
A novel cobalt-free perovskite based on Ba_(0.5)Sr_(0.5)Fe_(0.8)Zn_(0.2)O_(3-δ)(BSFZ)were prepared by EDTA-citric acid method.The lattice constants of the BSFZ perovskite were characterized by in situ high-temperature X-ray diffraction(HTXRD).The thermal expansion coefficient of BSFZ is 10.5×10~(-6)K~(-1),which is lower than that of cobalt-based perovskite materials.The BSFZ membrane was also used to construct reactors for the partial oxidation of methane(POM)to syngas.Results show that the BSFZ membrane... 相似文献
103.
A novel BaCe0.4Zr0.3 Sn0.1Y0.2O3−δ (BSY) electrolyte membrane with thickness of 20 μm was fabricated on NiO-based anode substrate via a one-step all-solid-state method followed by a co-sintering at 1450 °C for 5 h. Chemical stability test demonstrated that BSY electrolyte showed adequate chemical stability against CO2 and H2O at intermediate temperature. Besides, the doping of Sn also enhanced the conductivity in humidified hydrogen. With Nd0.7Sr0.3MnO3−σ cathode and hydrogen fuel, the fuel cell generated maximum output of 320, 185 and 105 mW cm−2 at 700, 650 and 600 °C, respectively. The interfacial resistance of the fuel cell was studied under open circuit conditions and the short-term cell performance also confirmed the stability of BSY electrolyte membrane. 相似文献
104.
Polyelectrolyte multilayer films adsorbed on gold surfaces were studied by combined ellipsometric and electrochemical methods. Multilayers were composed of “synthetic” (poly(4-styrenesulfonic acid) ammonium salt (PSS) and poly(allylamine hydrochloride) (PAH) (PSS/PAH)) and “semi-natural” (carboxymethyl cellulose (CMC) and chitosan (CHI) (CMC/CHI)) polyelectrolytes. It was found that only PSS/PAH Layer-by-Layer (LbL) assembled structures result in dense surface confined films that limit permeability of small molecules, such as ferri-/ferrocyanide. The PSS/PAH assemblies can be envisaged as films with pinholes, through which small molecules diffuse. During the LbL deposition process of these films a number of pinholes quickly decay. A representative pinhole diameter was found to be approximately 20 μm, which determines the diffusion of small molecules through LbL films, and yet remains constant when the film consists of a few LbL assembled polyelectrolyte bilayers. CMC/CHI LbL assemblies at gold electrode surfaces give very low density films, which do not limit the diffusion of ferri-/ferrocyanide between the surface of the electrode and the solution. 相似文献
105.
Serpil Ylmaztürk Hüseyin Deligz Mesut Ylmazolu Hakan Damyan Faruk
ksüzmer S. Naci Ko Ali Durmu M. Ali Gürkaynak 《Journal of membrane science》2009,343(1-2):137-146
A series of highly proton conductive electrolyte membranes with improved methanol barrier properties are prepared from polyallylamine hydrochloride (PAH) and polystyrene sulfonic acid (PSS) including salt by Layer-by-Layer (LbL) method. The effects of added salt type (NaCl, MgCl2) and salt concentration (1.0 M, 0.1 M) on proton conductivity (σ) and methanol barrier properties of the LbL self-assembled composite membranes are discussed in terms of controlled layer thickness and charge density. Furthermore, the influences of ion type in the multilayered composite membranes are studied in conjunction with physicochemical and thermal properties.The deposition of the self-assembly of PAH/PSS film on Nafion is followed by UV–Vis spectroscopy and it is observed that the polyelectrolyte layers growth on both sides of Nafion membrane regularly. (PAH/PSS)5–Na+ and (PAH/PSS)5–H+ with 1.0 M NaCl exhibits 49.6 and 27.8% reduction in lower methanol permittivity in comparison with the pristine Nafion®117, respectively, while the proton conductivities are 12.97 and 74.69 mS cm−1. Promisingly, it is found that the membrane selectivity values (Φ) of all multilayered membranes in H+ form are much higher than that of salt form (Na+ and Mg2+) and perfluorosulfonated ionomers reported in the literature. Also, we find out that the use of polyelectrolytes with high charge density causes a further improvement in proton conductivity and methanol barrier properties simultaneously. These encouraging results indicate that upon a suitable choice of LbL deposition conditions, composite membranes exhibiting both high proton conductivity and improved methanol barrier properties can be tailored for fuel cells. 相似文献
106.
Chemically crosslinked polyimide organic–inorganic composite nanofiltration membranes suitable for application in harsh organic solvents were successfully prepared by phase inversion of dope solutions. TiO2 nanoparticles were dispersed in these dope solutions, comprising polyimide (PI) in N,N-dimethylformamide/1,4-dioxane. The impact of TiO2 on the resulting PI membranes was investigated using SEM, TGA, water contact angle, dope viscosity measurements and mechanical strength. The presence of TiO2 nanoparticles within the membrane matrix was proved by the detection of a peak characteristic of TiO2 in the WAXS pattern. SEM pictures of the cross-section of the PI/TiO2 membranes showed dramatically changed morphology compared to reference membranes with no TiO2 addition. Macrovoids present in reference membranes were suppressed by increasing loading of TiO2 nanoparticles, and eventually disappeared completely at a TiO2 loading above 3 wt.%. Decreasing water contact angle and an increase in ethanol flux indicated that hydrophilicity increased as nanoparticle loading increased. The effect of TiO2 on the functional performance of the membranes was evaluated by measuring flux and rejection using cross-flow filtration. Perhaps surprisingly, the presence of TiO2 improved the compaction resistance of the membranes, whereas rejection and steady flux were almost unaltered. 相似文献
107.
108.
应用膜乳化-液中干燥法成功制备出粒径为2~20μm的单分散聚苯乙烯(PS)微球.PS微球的粒径主要由膜孔径决定,其值约为膜孔径的2倍;PS溶液的浓度对其也有一定的影响.膜乳化过程中的压力对微球粒径的分散性有很大的影响,在一定压力范围内,粒径呈单分散.在分散相中加入致孔剂,制备出表面多孔的PS微球.采用复乳-液中干燥法制备出中空PS微球. 相似文献
109.
Weiting Yu Junzhang Lin Xiudong Liu Hongguo Xie Wei Zhao Xiaojun Ma 《Journal of membrane science》2010
The semi-permeable membrane of alginate–chitosan (AC) microcapsules has been proven important to control the microcapsule stability and selective substance diffusion rate. Therefore, a novel and operable methodology based on gel permeation chromatography (GPC) was established for quantitative characterization of the membrane formation process, so as to provide guidance on performance improvement of AC microcapsules in biomedical applications. Not only the molecular weight (Mw) and its distribution of chitosan can be obtained by GPC, but also the area integral of molecular weight peaks can be linearly correlated to chitosan concentration in certain range. The dynamic membrane formation process was then obtained by quantitatively analyzing reaction amount of chitosan with time, which showed that for chitosan molecules with wide Mw distribution, only parts of molecules bind with alginate to form microcapsule membrane. Moreover, the contribution of chitosan molecules participating in the membrane formation process was also different. These new findings, therefore, are helpful for adjusting and controlling the membrane formation process and properties of microcapsule membrane. 相似文献
110.
Dragana Mutavdžić Pavlović Sandra Babić Davor Dolar Danijela Ašperger Krešimir Košutić Alka J. M. Horvat Marija Kaštelan‐Macan 《Journal of separation science》2010,33(2):258-267
This paper focuses on the investigation of different types of SPE sorbents for the preconcentration of eight veterinary pharmaceuticals from water samples. The pharmaceuticals studied were sulfamethazine, sulfadiazine, sulfaguanidine, trimethoprim, oxytetracycline, enrofloxacin, norfloxacin and penicillin G/procaine. Five different SPE materials (Strata‐X, Strata‐X‐C, Strata SDB‐L, Strata C8 and Strata C18) from Phenomenex were compared with Oasis HLB with a view to obtaining the best cartridges for all pharmaceuticals investigated. Extraction efficiency was determined by HPLC with diode array detection (DAD). HPLC‐DAD separation and quantification of the selected pharmaceuticals were carried out under gradient elution by a binary mixture of 0.01 M oxalic acid and ACN based on cyano modified column (LiChrosphere 100 CN) from Merck. Strata‐X provided the best results in the preconcentration of 100 mL water samples, yielding average pharmaceutical recoveries of higher than 90%, except for sulfaguanidine (76.1%). The developed Strata‐X‐HLPC‐DAD method was validated and applied, for the efficient investigation of reverse osmosis/nanofiltration membranes and for the removal of these eight pharmaceuticals from the production wastewater samples. NF90 and XLE membranes were shown to be the best for the rejection of all investigated pharmaceuticals. 相似文献